Instrumentation and method for implant insertion

ABSTRACT

An implant insertion apparatus for guiding surgical instrumentation and facilitating insertion of surgical implants into an intervertebral space, having a retractor positionable with respect to adjacent vertebrae in the intervertebral space and an adjustable element mounted to the retractor. The adjustable element defines a longitudinal passageway dimensioned to guide the surgical instrumentation inserted therethrough, and the length of the adjustable element is variable to provide varying drilling depth for the implantation.

BACKGROUND

[0001] 1. Technical Field

[0002] The present disclosure generally relates to a method andassociated instrumentation for implant insertion and, in particular, toa method and instrumentation for insertion of spinal implants tofacilitate fusion of adjacent vertebral bodies.

[0003] 2. Background of the Related Art

[0004] A large number of orthopedic procedures involve the insertion ofeither natural or prosthetic implants into bone or associated tissues.These procedures include, for example, ligament repair, joint repair orreplacement, non-union fractures, facial reconstruction, spinalstabilization and spinal fusion. In a typical procedure, an insert,dowel or screw is inserted into a prepared bore formed in the bone ortissues to facilitate repair and healing. Some implants are particularlyconfigured with cavities and bores to facilitate bony in-growth andenhance anchoring of the implant at the insertion site. Implants in theform of fusion cages having internal cavities to receive bone growthstimulation materials such as bone chips and fragments are disclosed,for example, in U.S. Pat. No. 4,501,269 to Bagby; and U.S. Pat. No.4,961,740 to Ray et al. These types of implants are particularly wellsuited for intervertebral spinal fusion procedures necessitated byinjury, disease or some degenerative disorder of the spinal disc.Subsequently, there may be progressive degeneration leading tomechanical instability between adjacent vertebrae necessitating directfusion of the vertebrae while maintaining a pre-defined intervertebralspace. This fusion may be accomplished by the insertion of one or moreof the specialized implants as discussed above and also discussed incommonly assigned U.S. Pat. No. 5,026,373, the contents of which areincorporated herein by reference.

[0005] Both anterior (transabdorninal) and posterior surgical approachesare used for interbody fusions of the lumbar spine. Fusions in thecervical area of the spine are primarily performed using a posteriorapproach. Typically, an implant such as a plug, dowel, prosthesis orcage is inserted into a preformed cavity inside the interbody,interdiscal space. Since it is desirable in these procedures to promotea “bone to bone” bridge, connective tissue and at least a portion of thedistal tissue is removed. Preferably, relatively deep cuts are made inthe adjacent bones in order to penetrate into the softer, morevascularized cancellous region to facilitate bone growth across theimplant.

[0006] One of the more critical tasks performed in the insertion of asurgical fusion implant, particularly, in intervertebral spinal fusion,is the formation of the implant receiving cavity or bore between/withinthe adjacent vertebrae. More particularly, the drilled bore must beequally centered within the intervertebral space and preferably parallelto the vertebral end plates to ensure removal of equal portions of bonefrom the adjacent vertebrae throughout the length of the cut andsubsequent appropriate seating of the implant relative to the vertebralbodies. In addition, the length of the cut by the drill must be accuratedepending upon the particular surgical needs for the patient and/or thelength of the implant to be inserted.

[0007] Surgical instruments for spinal fusion implant insertion areknown. Among several instruments, for example, U.S. Pat. No. 6,083,225to Winslow et al., the contents of which are incorporated herein byreference, discloses an improved type of instrumentation and method forproviding optimal alignment for the drilling, tapping and reception ofspinal implant. This method uses a particular surgical retractor forinserting into the intervertebral space to distract adjacent vertebraeand performing the surgical procedure with instrumentation insertedthrough an opening of the surgical retractor.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to further improvements inspinal fusion procedures. In accordance with one aspect of the presentinvention, an improved instrumentation and associated method tofacilitate the introduction of fusion implants, which ensures convenientadjustment of the drilling depth for reception of the fusion implantsand, if appropriate, for bore tapping procedures, is provided. Anotheraspect of the present invention is to provide an improvedinstrumentation and associated method to facilitate the introduction offusion implants, which further ensures simplified and effectiveprocedures for the implantation of two implants in side-by-side orlateral relation.

[0009] In accordance with the present disclosure, an implant insertionapparatus includes a retractor having a longitudinal openingtherethrough. The retractor is positionable across an intervertebralspace with respect to the adjacent vertebrae to maintain the adjacentvertebrae at a predetermined spaced relation. The insertion apparatusfurther includes an adjustable element defining a longitudinalpassageway for the surgical instrumentation inserted therethrough. Thelength of the adjustable element is adjustable. Thus, by adjusting thelength of the adjustable element, the depth of drilling to form theimplant receiving bore within the adjacent vertebrae may be preciselycontrolled.

[0010] The present disclosure is also directed to a method forperforming a surgical procedure with the implant insertion apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Preferred embodiments of the disclosure are described hereinbelowwith reference to the drawings wherein:

[0012]FIG. 1 is a perspective view illustrating an implant insertionapparatus constructed in accordance with one embodiment of the presentinvention including a retractor, adjustable element and handle;

[0013]FIG. 2A is a perspective view similar to the view of FIG. 1illustrating disengaging of retractor from the adjustable element;

[0014]FIG. 2B is a partial cross-sectional view of the adjustableelement taken along the lines A-A of FIG. 2A, illustrating locking oflocking screws to provide length adjustment for the adjustable element;

[0015]FIG. 3 is a perspective view of an alternate embodiment of theimplant insertion apparatus of FIG. 1;

[0016]FIG. 4 is a view similar to the view of FIG. 3 illustrating anassembled implant insertion apparatus;

[0017]FIG. 5 is a perspective view of another alternate embodiment ofthe implant insertion apparatus of FIG. 1;

[0018]FIG. 6 is a perspective view of another alternate embodiment ofthe implant insertion apparatus of FIG. 1;

[0019]FIG. 7 is a perspective view of a surgical kit utilized forinsertion of a fusion implant including, from bottom to top, an implantinsertion instrument and fusion implant, a tap instrument, a drillinstrument and a T-shaped handle;

[0020]FIG. 8 is a top cross-sectional view of an intervertebral spacedefined between adjacent vertebrae illustrating insertion of the implantinsertion apparatus of the present disclosure;

[0021]FIG. 9 is a side cross-sectional view of the vertebral columnfurther illustrating positioning of the implant insertion apparatushaving a handle connected to the retractor, in accordance with theprinciples of the present disclosure;

[0022]FIG. 10 is a view similar to the view of FIG. 8 illustratingpositioning of the retractor in one lateral side of the intervertebralspace and insertion of an implant insertion apparatus in the otherlateral side of the space;

[0023]FIG. 11 is a view similar to the view of FIG. 9 illustratinginsertion of the drill instrument into the implant insertion apparatusto drill a bore within the adjacent vertebrae;

[0024]FIG. 12 is a view similar to the view of FIG. 11 illustratinginsertion of the tap instrument into the implant insertion apparatus totap the bore formed by the drill instrument;

[0025]FIG. 13 is a perspective view illustrating insertion of theimplant insertion instrument with mounted implant into the retractor toinsert the implant; and

[0026]FIG. 14 is a view illustrating insertion of a pair of fusionimplants into the intervertebral space.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0027] The preferred embodiments of the method and instrumentationdisclosed herein are discussed in terms of orthopedic spinal fusionprocedures and instrumentation. It is also envisioned, however, that thedisclosure is applicable to a wide variety of procedures including, but,not limited to ligament repair, joint repair or replacement, non-unionfractures, facial reconstruction and spinal stabilization. In addition,it is believed that the present method and instrumentation findsapplication in both open and minimally invasive procedures includingendoscopic and arthroscopic procedures wherein access to the surgicalsite is achieved through a cannula or small incision.

[0028] The following discussion includes a description of eachinstrument utilized in performing a spinal fusion followed by adescription of the preferred method for spinal fusion utilizing theinstrumentation in accordance with the present disclosure.

[0029] In the discussion which follows, the term “proximal”, as istraditional, will refer to the portion of the structure which is closerto the operator, while the term “distal” will refer to the portion whichis further from the operator.

[0030] Referring now to the drawings in which like reference numeralsidentify similar or identical elements throughout the several views,FIGS. 1-2B illustrate in perspective views an implant insertionapparatus constructed according to the principles of the presentdisclosure. Implant insertion apparatus 10 includes retractor 20 andadjustable element 30. The adjustable element 30 includes elongate body40 releasably mounted to the retractor 20, and extended body 50. Theinsertion apparatus 10 is particularly contemplated for distractingadjacent bony structures, e.g., adjacent opposed vertebral bodies, forproviding an opening to facilitate insertion of surgicalinstrumentation, and for ensuring proper alignment of theinstrumentation and accurate insertion of the implant. Althoughdescribed for spinal procedures, it is envisioned that insertionapparatus 10 may also be utilized to distract other structures as wellincluding joints, ligaments, etc.

[0031] Retractor 20 includes base portion 22 having a proximal endportion 24 and a distal end portion 26 and longitudinal opening 27extending therethrough. Retractor 20 further includes first and secondspacer arms 28 extending longitudinally from the distal end 26 of baseportion 22. Each spacer arm 28 defines a first vertebra supportingsurface 28 a to contact a first vertebra and a second vertebrasupporting surface 28 b to contact a second vertebra with the surfaces28 a and 28 b preferably being in general parallel relation to eachother. The height “h” of each arm 28 ranges from about 0.3 to 0.4 inchesand more preferably from about 0.28 to about 0.35 inches. One skilled inthe art will readily appreciate that this dimension can be varied asneeded depending upon the procedure. Each arm 28 further includestapered end portions 28 c defining a generally V-shaped configuration.End portions 28 c facilitate insertion of the arms 28 within thesurgical site, e.g. within the intervertebral space. The retractor 20further includes a mounting portion 29 in the proximal end 24 of thebase portion 22 for mounting the adjustable element 30 as describedbelow.

[0032] Referring still to FIGS. 1-2B, the elongate body 40 includes acorresponding mounting portion 41 (FIG. 2A) at its distal end formounting to the retractor 20. The mounting portion 29 and thecorresponding mounting portion 41 may be a bayonet connection of knowntypes (as illustrated), or may be other types of configuration, e.g., athreaded connection. The elongate body 40 includes proximal and distalrims 42, 44, first and second extending portions 46 and at least onescrew receiving hole 48 therein.

[0033] With continued reference to FIGS. 1-2B, the extended body 50includes an elongate member 52 and proximal and distal rims 54, 56defining a longitudinal passageway 58 therethrough for receivingsurgical instrumentation described below. The inner diameter of the rims54, 56 together with the inner surface of the elongate member 52 ispreferably dimensioned such that the rim 42 and the extending portions46 slidably fits therewithin. The extended body 50 further includes atleast one positioning groove 59 formed in the elongate member 52. Thegroove 59 extends along the elongate member 52 and has locking portions59 a to receive locking nuts (described below). The number of thelocking portions 59 a ranges from 2 to 10, and may be varied dependingupon particular surgical needs. The distance between adjacent lockingportions ranges from 2 mm to 30 mm, and may also be varied. The elongatemember 52 may include length markings (not shown) around the groove 59for providing indication of relative longitudinal positioning of theextended body 50 with respect to the elongate body 40, and further fordetermining in advance the ultimate penetrating depth of the surgicalinstrumentation into the intervertebral space.

[0034] The insertion apparatus 10 further includes at least one lockingnut 60 for threadably engaging locking screw 62 which is fixedly mountedwithin the hole 48 of the elongate body 40. The locking nut 60 includespositioning end 60 a for engaging the locking portion 59 a of the groove59 to provide the longitudinal positioning of the extended body 50 withrespect to the elongate body 40. It should be noted that the extendedbody 50 is slidably movable along the elongate body 40 when positioningend 60 a is disengaged from locking portion 59 a. Securement of thelocking nut 60 is achieved by threadably advancing the locking nut 60into position within the locking portion 59 a. The overall length fromthe distal end of the retractor 20 to the proximal end of the extendedbody 50 is adjustable by locking the locking nut 60 in the locking screw62 after positioning in the desired location.

[0035] Referring still to FIGS. 1-2B, insertion apparatus 10 furtherincludes a retractor handle 70, consisting of a connecting bar 72 with aconnecting screw thread 74 at its distal end and a handle 76 at theproximal end of the connecting bar 72. Handle 70 is connected toretractor 20 through threaded connection of screw thread 74 withinternal thread disposed within connecting portion 22 a of retractor 20.The connecting portion 22 a and the retractor handle 70 are provided foraiding manipulation of the retractor 20 or the insertion apparatus 10for the surgical procedure, as described herein below.

[0036] Referring now to FIGS. 3-4, which illustrate an alternativeembodiment of the present disclosure, implant insertion apparatus 100includes retractor 120 and adjustable element 130. The adjustableelement 130 includes elongate body 140 releasably mounted to theretractor 120, and extended body 150. Retractor 120 is substantiallysimilar to the retractor 20 discussed in connection with the embodimentsof FIGS. 1-2A, but, however includes a threaded portion whichfacilitates mounting for the adjustable element.

[0037] The elongate body 140 includes a corresponding mounting portion141, i.e., in the form of an internal thread, which threadably receivesthe threaded portion of retractor 120. The mounting portion 129 and thecorresponding mounting portion 141, may be thread-type configurations asshown, or may be other types of configuration, e.g., a bayonetconnection. The elongate body 140 may include first and secondlongitudinally extending openings 142 and at least one screw-receivingthreaded hole 148, both the openings 142 and the holes 148 formed in itsouter wall. Openings 142 are diametrically arranged with relation toeach other. Each opening 142 extends radially for about between 10%-50%the circumference or perimeter of the body 140 and longitudinally forgreater than 50% the length of the body 140. Openings 142 arecontemplated to permit the lateral introduction of surgicalinstrumentation required to carry out the fusion procedure as analternative to introducing the instrumentation through the longitudinalopening 144. These openings 142 also enhance illumination at thesurgical site.

[0038] With continued reference to FIGS. 3-4, the extended body 150includes an elongate member 152 defining a longitudinal passageway 154therethrough for receiving surgical instrumentation described below. Theouter diameter of the member 152 is preferably dimensioned such that themember 152 slidably fits within the opening 144 of the elongate body140. The extended body 150 further includes at least one positioninggroove 156 formed in its outer wall of the member 152. The groove 156may be complete holes pierced through the wall of the member 152, or maybe a groove formed only in the outer surface of the member 152. Thegrooves 156 may be one extended groove having locking portions 156 a (asshown in FIG. 3), or may be multiple separate holes or grooves 159 (asshown in FIG. 5). The number of holes or locking portions ranges from 2to 10, and may be varied depending upon particular surgical needs. Thedistance between adjacent holes or locking portions ranges from 2 mm to30 mm, and may be varied depending upon particular surgical needs. Theextended body 150 may include length markings 158 in its outer wall forproviding indication of relative longitudinal positioning of theextended body 150 with respect to the elongate body 140, and further fordetermining in advance the ultimate penetrating depth of the surgicalinstrumentation into the intervertebral space.

[0039] The insertion apparatus 100 further includes at least one lockingscrew 160 for engaging the screw receiving hole 148 by a threadedportion 160 a. The screw 160 includes a positioning end 160 b forengaging the groove portion 156 of the extended body 150 to provide thelongitudinal positioning of the extended body 150 with respect to theelongate body 140. The overall length from the distal end of theretractor 120 to the proximal end of the extended body 150 is adjustableby locking the screw 160 in the desired locking portion 156 a.

[0040] The insertion apparatus 100 may further include a head portion161 connected to the proximal end of the extended body 150 for receivingimpact of a driving member for insertion of retractor 120 of theinsertion apparatus 100 into the intervertebral space. The head portion161 includes an opening 162 for receiving the surgical instrumentation.The head portion 161 may be fixedly connected to the extended body 150,or may be longitudinally adjustable with at least a portion of the innersurface of the opening 162 including a threaded portion 164, as it is inthe corresponding portion of the extended body 150. An additionallongitudinal adjustment may, if needed at all, be performed by turningthe head portion 161 with respect to the extended body 150, thusproviding a fine adjustment in addition to the primary adjustment madeby the screw 160 and grooves 156 as described above. The depth-adjustingprocess may be further aided by reading the indication of lengthmarkings 158. In addition, the head portion 161 may include additionalmarkings 158 a in its distal facing surface 168. The penetrating depthmay be finely adjusted by turning back or forth the head 161 around theextended body 150 while reading the additional markings 158 a or readingthe length markings 158.

[0041] Referring now to FIG. 5, which illustrates another alternativeembodiment of the present disclosure and is in similar structure to theembodiment described with FIGS. 3-4, extended body 150 a may include, asan alternative to the groove 156, a plurality of holes 159 for receivingthe screw 160 to adjust the depth of the adjustable element 130. Thenumber of the holes may be varied depending upon the particular surgicalneeds.

[0042] Referring now to FIG. 6, which illustrates another alternativeembodiment of the present disclosure, the insertion apparatus 100 bincludes, as an alternative to the retractor 20 or 120 in FIGS. 1-5, anengaging member 180 having tacks 182 for inserting and mounting to thetissue, e.g., adjacent vertebrae across an intervertebral space. Thenumber and size of the tacks may be varied depending upon the particularsurgical needs. The engaging member 180 includes a base portion 184having a proximal end portion and a distal end portion. The base portion184 includes a longitudinal opening 186 therethrough between theproximal end and the distal end of the base portion 184. The engagingmember 180 further includes a bayonet-type mounting portion 188 in theproximal end of the base portion 184. The insertion apparatus 100 bfurther includes an elongate body having a corresponding mountingportion 188 b in its distal end. As described above such mounting may beachieved by other types of releasable connection, e.g., thread-typeconnection. The elongate body 140 b may be in a similar structure asdescribed above with FIGS. 3-4.

[0043] Referring still to FIG. 6, the insertion apparatus 100 b furtherincludes extended body 150 b having similar structure described above.The extended body 150 b includes at least one groove 156 b formed in theouter surface of the member 152 b, i.e., the groove being built withoutpiercing through the wall of the member 152 b. By locking the screw 160onto the groove 156 b, length adjustment can be achieved in anylongitudinal positions along the length of the groove 156 b. Theadjustable element may alternatively include positioning dents 156 dformed along in the groove 156 b to receiving the distal tip 160 c ofthe screw 160 and getting multiple predetermined positioning.

[0044] Referring now to FIG. 7, the various other instrumentscontemplated for use in the spinal fusion procedure are illustrated,including surgical drill 200, surgical tap instrument 300, implantinsertion instrument 400 with implant 500 and T-shaped handle 600. Drillinstrument 200 includes drill shaft 202, extension shaft 204 and drillbit 206 mounted at the distal end of the drill shaft. Extension shaft204 has a collar 208 to control, together with the insertion apparatus10, the depth of penetration of drill shaft 202 and drill bit 206 intoadjacent vertebrae. Drill shaft 202 includes a hexagonal-shaped head 212at its proximal end to mount T-handle 600.

[0045] Tap instrument 200 is disclosed in the Winslow ′225 patentmentioned above. Tap instrument 300 is utilized for performing aninternal thread within the drilled bore formed by the drill instrument.Tap instrument 300 includes elongated member 302 having hex head 304 atits proximal end to engage T-shaped handle 600. Tap instrument 300further includes distal tapping threaded portion 306. Distal tappingportion 306 includes a plurality of conveyance channels (one is shown)308 extending longitudinally through the cutting thread. Each conveyancechannel 308 has a directional component parallel to the longitudinalaxis and a directional component transverse to the longitudinal axis.Each conveyance channel 308 encompasses approximately an arc of about{fraction (1/3)} the outer circumference of the tapping portion 306Conveyance channels 308 are each dimensioned to receive bone materialdeburred by the cutting edges during the tapping procedure and tocontinually transmit the bone material proximally through the channel toavoid undesired material build up at the tapping site. In this manner,tapping instrument 300 may be used to completely tap the internal threadwithin the bore without interruption of the tapping procedure.

[0046] Implant insertion instrument 400 is also disclosed in the Winslow′225 patent. It should be noted that the tap need not be used if aself-tapping implant is utilized. Implant insertion instrument 400includes elongated member 402 having proximal mounting portion 404 toengage T-shaped handle 600 and distal portion 406 which mounts implant500. Distal portion 406 includes cylindrical mount 408 which is receivedwithin the bore of the implant 500 and implant engaging ball 410 whichis received within an aperture defined in the wall of the implant 500 topositively fix the implant to the instrument A hand lever 412 isproximally located and is operatively connected to an inner drive member(not shown) disposed within elongated member 402. The hand lever 412 islongitudinally movable to translate the drive member which, in turn,moves through a camming action implant engaging in ball 410 between anoutward position in engagement with the implant 500 and an inwardposition released from the implant 500.

[0047] Implant 500 is uniquely designed for use in spinal fusionprocedures. This implant 500 is generally disclosed in U.S. Pat. No.5,026,373 to Ray, the contents of which have been previouslyincorporated herein by reference, and is commonly referred to as a“fusion cage”. Implant or fusion cage 500 includes a cylindrical cagebody 502 having an internal cavity or hole for accommodating bone-growthinducing substances. One end 504 of cage body 502 is closed and definesa rounded or bull-nosed configuration to facilitate insertion of thefusion cage relative to one or more bony structures. The other enddefines an opening which communicates with the internal cavity. Theouter surface of the cage body 502 includes a single continuous thread506 (preferably V-shaped) having a plurality of raised turns withvalleys defined between adjacent turns.

[0048] A plurality of perforations 508 are disposed within the threadsand extend through the outer surface of the cage body 502 to providedirect communication between the outer surface and internal cavity 504.The perforations 508 permit immediate contact between the bone growthinducing substances within the inner cavity and the bone structure whenthe cage body 502 is mated to the bone structure, e.g., adjacentvertebrae. An end cap (not shown) may be mountable to the open end ofcage body 502 to enclose the bone-growth inducing substances within theinterior cavity.

[0049] T-shaped handle 600 includes mounting portion 602 defininghexagonal-shaped recess 604 which receives the corresponding structureof drill instrument 200, tap instrument 300 and implant insertioninstrument 400.

Application of Instrumentation

[0050] The use of the instrumentation in conjunction with the insertionof the fusion cage 500 into an intervertebral space defined betweenadjacent vertebrae will be described. The subsequent description will beparticularly focused on an open posterior spinal fusion procedure, usingtwo implants in side-by-side relation. However, it is to be appreciatedthat an anterior approach or a singular implant insertion approach iscontemplated as well.

[0051] The intervertebral space is accessed utilizing appropriateinstrumentation to expose the posterior vertebral surface. Then, thedesired-sized vertebral retractor 20, or engaging member 180, isselected and mounted to the adjustable element 30 by cooperation ofcorresponding mounting portions 29, 41 (FIG. 2A) of the retractor andthe elongate body 40. With reference to FIG. 8, a first lateral side ofthe intervertebral space “i” is targeted. By manipulating the insertionapparatus 10, spacer arms 28 of the retractor 20 is inserted within theintervertebral space “i” adjacent the first lateral side. A standardmallet may be utilized to impact the proximal end of the apparatus 10,or alternatively elongate body 30, to drive spacer arms 28 into the discspace. Spacer arms 28 are inserted in a manner such that first andsecond supporting surfaces 28 a, 28 b of each spacer arm 28 respectivelyengage the opposed vertebral bodies “v₁ v₂” as depicted in FIG. 9. Oncein position, the adjustable element 30 is removed from the retractor 20by rotating to disengage the respective mounting portions 29, 41 therebyleaving the retractor 20 within the intervertebral space. As shown inFIG. 9, the retractor 20 may include connecting portion 22 a (shown thedetails in FIG. 1), and the insertion apparatus 10 may further include aretractor handle 70 releasably connected to the connecting portion 22 a.By holding the retractor handle, the removal of the adjustable element30 may be further secured without dislodging or harmful movement in anydirection. Thereafter, the retractor handle 70 may also be removed fromthe retractor 20. The spacer arms 28 of retractor 20 are appropriatelydimensioned to stabilize the desired lateral side of the intervertebralspace. It is to be noted that retractor 20 may distract the adjacentvertebrae “v₁ v₂” as desired to become firmly implanted within theintervertebral space “i”.

[0052] With reference now to FIG. 10, insertion apparatus 10 includinganother retractor 20 is likewise inserted within the intervertebralspace “i” adjacent the other lateral side thereof. The apparatus 10 maybe inserted by impacting the proximal end of the apparatus 10 into theintervertebral space “i”. Upon insertion of spacer arms 28, thevertebral bodies “v₁ v₂” are distracted whereby the arms 28 becomefirmly lodged within the intervertebral space. The retractor 20 selectedpreferably corresponds in dimension to the first retractor 20 to ensureparallel distraction of the adjacent vertebrae “v₁ v₂” so as to maintaina predetermined spacial distance of the vertebrae across the span of theintervertebral space “i”.

[0053] Referring now to FIG. 11, the surgical drill instrument 200 isnow utilized to prepare the disc space and vertebral end plates forinsertion of the fusion implant. The cutting depth of drilling isadjusted in advance as desired by utilizing the telescopiclength-adjusting features of the present invention: i.e., first, theoverall length of the adjustable element 30 is set by positioning distalend portion of the screw 62 into an appropriate locking portion 59 a ofthe groove 59; then, locking nut 60 is advanced until positioning end 60a (FIG. 2B) securely engages locking portion 59 a of the groove 59. Itshould be noted that the depth adjustment utilizing the element 30 maybe alternatively performed before insertion of the apparatus 10 into theintervertebral space. Now, with the T-handle mounted to surgical drillinstrument 200, the instrument is introduced into the axial bore ofretractor 20 and advanced to contact the posterior surface of thevertebral bodies, “v₁ v₂”. Drill 200 is advanced into the intervertebralspace “i” by rotating T-handle 600 such that drill bit 200 shears thesoft tissue and cuts the bone of the adjacent vertebrae “v₁ v₂” therebyforming a bore which extends into the adjacent vertebrae “v₁ v₂” untilstopping collar 208 contacts the proximal end surface of rim 54. Drill200 is then removed from insertion apparatus 10. It is to be noted thatduring the bore forming process, the pre-inserted retractor 20 inconjunction with the current retractor 20 stabilize the adjacentvertebrae “v₁ v₂” (e.g., the first and second lateral sides of theintervertebral space are stabilized by retractor arms 28 of the tworetractors 20) to minimize lateral and/or longitudinal movement of thebodies and also to facilitate the formation of a uniform bore within theend plates.

[0054] Referring now to FIG. 12, tap instrument 300 is selected andattached to the T-handle 600. Tap instrument 300 is inserted intoinsertion apparatus 10 and positioned adjacent the drilled bore formedin the adjacent vertebrae “v₁ v₂” by the surgical drill 200. Withinsertion apparatus 10 as a direct guide, T-handle 600 is rotated in thedirection of the directional arrow of FIG. 12 while simultaneouslyapplying sufficient downward pressure on the T-handle to advance the tapinstrument 300 and promote even purchase into the endplates. Uponadvancement of the tap instrument 300, the deburred bone chips collectwithin conveyance channel 308 of tapping head 306, and are conveyedproximally during rotational movement of the tapping head away from thetapping site. Tap instrument 300 is advanced into the bone until thedesired depth has been achieved, which occurs when the distal end oftapping head 308 “bottoms out” on the bone. When tap instrument 300reaches the appropriate depth, the tap instrument 300 is rotated viaT-handle 600 in an opposite direction to back the instrument out of thebone.

[0055] With reference now back to FIG. 9, adjustable element 30 isremoved from the retractor 20 by disengaging the respective mountingportions 29, 41 thereby leaving the retractor 20 within theintervertebral space. The removal of the adjustable guide from theretractor may be further secured by holding retractor handle 70.

[0056] With reference now to FIG. 13, attention is focused on theinsertion of fusion implant 500. Cage body 502 is mounted onto insertioninstrument 400 by positioning the cage body 502 onto mounting portion408 of the instrument to permit mounting ball 410 to engage one of theapertures of the implant 500. This assembly is attached to T-handle 600.Insertion instrument 400 with mounted cage body 502 is inserted into theretractor 20 and the cage body 502 is positioned within the tapped boreby rotating insertion instrument 400 in the appropriate direction. Cagebody 502 is advanced until it is completely seated with the bore. Anindicator line 414 (FIG. 7) on insertion instrument 400 assists thesurgeon in determining when the cage is in proper position. Insertioninstrument 400 is then removed from retractor 20.

[0057] At this point in the procedure, bone growth inducing substancesmay be harvested from, e.g., the iliac crest, and packed into the cagebody 502 of implant 500 until the cage body 502 is completely filledwith bone growth inducing substances. An end cap may then be mounted tothe cage body 202. Retractor 20 is then removed by manipulating theretractor handle 70.

[0058] With implant 500 appropriately positioned in the second lateralside of the intervertebral space “i”, attention is directed to preparingthe first lateral side for insertion of a second implant. Adjustableelement 30 is now mounted to the previously inserted retractor 20 in thesame manner described above.

[0059] A second bore is formed in this first lateral side with drillingand tapping, if desired, followed by insertion of the implant aseffectuated in accordance with the methods and instruments describedabove in connection with FIGS. 7-13.

[0060]FIG. 14 illustrates two lateral fusion implants 500 insertedwithin the intervertebral space.

[0061] While the above description contains many specifics, thesespecifics should not be construed as limitations on the scope of thedisclosure, but merely as exemplifications of preferred embodimentsthereof. For example, it is envisioned that a self-tapping implant maybe utilized thus precluding the use of tap instrument 300. Those skilledin the art will envision many other possible variations that are withinthe scope and spirit of the disclosure as defined by the claims appendedhereto.

What is claimed is:
 1. An implant insertion apparatus for guidingsurgical instrumentation and facilitating insertion of surgical implantsinto an intervertebral space, comprising: an engaging elementpositionable with respect to adjacent vertebrae in the intervertebralspace; and an adjustable element mounted to the engaging element, theadjustable element defining a longitudinal passageway dimensioned toguide the surgical instrumentation inserted therethrough, wherein thelength of the adjustable element is variable.
 2. The implant insertionapparatus according to claim 1 wherein the adjustable element includesan elongate body releasably mounted to proximal end of the engagingelement, and an extended body movable along the elongate body.
 3. Theimplant insertion apparatus according to claim 2 further includingpositioning members for setting relative positions of the extended bodywith respect to the elongate body to adjust the length of the adjustableelement.
 4. The implant insertion apparatus according to claim 3 whereinthe positioning members includes at least one positioning groove in theadjustable element and a locking element to engage the positioninggroove.
 5. The implant insertion apparatus according to claim 1 whereinthe engaging element includes a base having a proximal end and a distalend, and defining a longitudinal opening therethrough.
 6. The implantinsertion apparatus according to claim 5 wherein the engaging elementfurther includes first and second spacer arms extending longitudinallyfrom the distal end of the base, each spacer arm defining a firstvertebra supporting surface to contact a first vertebra and a secondvertebra supporting surface to contact a second vertebra.
 7. The implantinsertion apparatus according to claim 5 wherein the engaging elementfurther includes a plurality of tacks for mounting to the adjacentvertebrae.
 8. The implant insertion apparatus according to claim 1wherein the adjustable element is releasably mounted to the engagingelement by a bayonet-type connection.
 9. The implant insertion apparatusaccording to claim 1 wherein the adjustable element is releasablymounted to the engaging element by a thread-type connection.
 10. Theimplant insertion apparatus according to claim 1 further including alength indicator for indicating the adjusted length of the implantinsertion apparatus.
 11. The implant insertion apparatus according toclaim 1 further including a handle mounted to the engaging element. 12.The implant insertion apparatus according to claim 1 further including ahead mounted to a proximal end of the adjustable element, the headhaving a greater cross-sectional dimension for receiving impact of adriving member for positioning the engaging element with respect to theadjacent vertebrae.
 13. The implant insertion apparatus according toclaim 12 wherein the head is longitudinally adjustably mounted to theadjustable element and includes an opening to insert theinstrumentation.
 14. A method for performing a surgical procedurecomprising the steps of: providing an implant insertion apparatuscomprising a retractor positionable with respect to adjacent vertebraeand defining a longitudinal opening therethrough, and an adjustableelement releasably mounted to the retractor and defining a longitudinalpassageway for reception of surgical instrumentation; adjusting thelength of the adjustable element; positioning the implant insertionapparatus with respect to adjacent vertebrae across an intervertebralspace with the retractor at least partially engaged to the adjacentvertebrae to maintain the adjacent vertebrae in predetermined spacedrelation; and introducing surgical instrumentation within thelongitudinal passageway of the adjustable element to perform a surgicalprocedure.
 15. The method according to claim 14 wherein the step ofintroducing includes advancing a surgical drill through the implantinsertion apparatus to drill a bore within the adjacent vertebraewhereby the depth of advancement of the drill is controlled by thelength of the adjustable element.
 16. The method according to claim 15further including the step of releasing the adjustable element from theretractor.
 17. The method according to claim 16 wherein the step ofintroducing includes advancing a surgical implant through thelongitudinal opening of the retractor and into the bore within theadjacent vertebrae.
 18. A method for performing a surgical procedure forimplantation of at least two implants in side-by-side relation,comprising the steps of: providing at least two engaging elements, eachengaging element being positionable with respect to adjacent vertebraeand defining a longitudinal opening therethrough, and at least oneelongate member releasably mounted to the engaging element and defininga longitudinal passageway for surgical instrumentation; accessing afirst intervertebral space with the first engaging element mounted tothe elongate member; positioning the first engaging element into thefirst intervertebral space with the first engaging element at leastpartially engaged to the adjacent vertebrae; releasing the elongatemember from the engaging element thereby leaving the engaging elementwithin the first intervertebral space; accessing a second intervertebralspace with the second engaging element mounted to the elongate member;positioning the second engaging element into the second intervertebralspace with the second engaging element at least partially engaged to theadjacent vertebrae; and performing the surgical procedure at the secondintervertebral space.
 19. The method for performing a surgical procedureaccording to claim 18, wherein the length of the elongate member isvariable, and the method further includes the step of adjusting thelength of the elongate member.
 20. The method for performing a surgicalprocedure according to claim 18 further comprising the steps of:accessing the first intervertebral space in which the first engagingelement was left therein with the at least one elongate member; mountingthe elongate member to the first engaging element at the firstintervertebral space; and performing the surgical procedure at the firstintervertebral space.
 21. The method for performing a surgical procedureaccording to claim 18 wherein the engaging element further includes ahandle releasably mounted thereto, and at least one of the steps are atleast partially assisted by holding the handle mounted to the engagingelement.